Gm Global Technolgoy Operations, Inc.

Vadim Rezhets

William F Jandeska, Jr

Carlo Ligotti

Bob Ross Powell

Aihua A Luo

Basant L Tiwari

A family of die castable, creep-resistant magnesium alloys has been developed for high-temperature structural applications such as automotive engines and transmission cases. These alloys contain between 3% and 6% aluminum, 1.7% and 3.3% calcium, and up to 0.2% strontium. They have demonstrated 25% greater tensile and compressive creep resistance than AE42, a commercial aluminum, rare earth containing magnesium alloy, and corrosion resistance as good as AZ91D. These alloys are estimated to cost less than AZ91D and have good castability in metal molds as used in permanent mold casting and die casting.

Creep-resistant magnesium alloy die castings

A powder metallurgy process for producing near-net shape, near-theoretical density structures of multiphase nickel, aluminum and/or titanium intermetallic alloys is provided by employing pressureless sintering techniques. The process consists of blending a brittle aluminide master alloy powder with ductile nickel powder, so as to achieve the desired composition. Then, after cold compaction of the powdered mixture, the compact is liquid phase sintered. The four step liquid phase sintering process is intended to ensure maximum degassing, eliminate surface nickel oxide, homogenize the alloy, and complete densification of the alloy by liquid phase sintering.

Powder metal process for producing multiphase NI-AL-TI intermetallic

A presinter treatment is provided to reduce oxygen contamination prior to sintering a predominantly iron powder compact comprising carbon powder and a liquating diffusible boron source, such as nickel boride powder optionally in combination with iron boride powder. A preferred treatment is carried out at a temperature effective to dissociate iron oxide within the compact but not to initiate a liquid phase by said boron source and further is carried out in a vacuum to evacuate oxygen released thereby from compact pores prior to sintering. The presinter treatment enhances carbon and boron diffusion into the iron during sintering. In a preferred embodiment, the fraction of borocementite particles formed by diffused carbon and boron in the sintered iron structure is increased by the presinter treatment of this invention.

Presinter treatment for iron powder article formed with boride additive

A sintering aid is disclosed for use in a powder metallurgical method for manufacturing an iron alloy article by compacting and sintering a predominantly iron powder mixture comprising carbon powder and a boron-containing additive, such as nickel boride. The sintering aid comprises an oxygen getter to inhibit boron oxidation that, if formed, is believed to retard carbon diffusion. The sintering aid also preferably includes a second constituent to produce, in combination with the getter, a melting point suitable for forming a transient liquid phase during the early stages of sintering. Preferred sintering aids include intermetallic iron titanium compounds, intermetallic ferro-vanadium compound and intermetallic nickel magnesium compound.

Method of producing iron powder article

A wear resistant iron alloy article is preferably formed by compacting and sintering a predominantly iron powder mixture containing additions of carbon, copper and nickel boride. The product microstructure comprises hard borocementite particles dispersed in a martensite or pearlite matrix. The particles have a cross-sectional dimension greater than 1 micron and are present in an amount preferably between 10 and 30 volume percent to improve wear resistance.

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West Bloomfield, MI, United States of America

Vadim Rezhets